O.K. I’ve got to raise an existing roof to add a second story. There are existing trusses with plywood sheathing and 3 tab shingles. How do I do this without damaging the existing roof? The house is not very big; only 24 X 36
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Replies
A big crain after the required bracing etc, has been signed off on by engineer is the general answer.
I believe there was either an article or discussion here about it in the not to distant past, maybe at JLC?
Yeah, I knew a crane would be involved, but that tells me nothing. How do you hook up the crane to the roof without the whole roof bowing and popping all the nails. And, I live in West Virginia: Engi..what?
I am in the process of looking up some articles on the issue without much luck. If you find it, let me know
Thanks
You hook up the crane the way the engineer tells you to so it doesn't do all those things. That way you're not liable, or least limit your liability, if something does go wrong.
If you've never done it before you're probably better off getting someone else to design the tie downs and bracing.
It was the Journal of Light Construction, April 1987, article by Henri deMarne, titled "Raising the Roof". They built the walls on the ground as panels, lifted the roof and plopped the walls in place. http://www.jlconline.com/cgi-bin/jlconline.storefront/46f49bcb001627c427177f00000105cd/Product/View/8704raisHere's another promising article from the search page:
http://www.jlconline.com/cgi-bin/jlconline.storefront/46f49bcb001627c427177f00000105cd/Product/View/9302asecAnd the search page:
http://www.jlconline.com/cgi-bin/jlconline.storefront/46f49bcb001627c427177f00000105cd/Export/catalogs/1014subRoof_Raising
didn't ya know yer supposed to walk this guy thru it step by step?
and oh yeah ... hurry up.
before he has to bump himself back to the top.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
O.K. It is not an emotional decission, it is a pure financial one. I think some people really overthink this thing. And is the motivation relevant? I don't think so.
I cannot build under it because it has block walls. It seems that the previous owners built a basement and even added floorjoists to it, then popped the trusses on top of the floor, some walls, presto, a house.
If anybody has found any articles I would appreciate knowing where they are. I haven't had much luck.
And, Jeff Buck, you do not need to walk me through it step by step I would just like advice from anybody who has actually done this specific task. I just wanted more than someone stating the obvious.
Thanks to all
you're missing the point mrhodes, you're ignoring the "obvious" which is you need an engineer to look at it for the truss roof.
What you're really saying is you don't like the answers you are getting here. It isn't often that people unanimously agree here.
The reason you're not finding to many articles is because (A) it's not done often, and (B) every instance is somewhat unique.
By emotional, I mean do you love the memories in teh house, do you love the location, the yard, etc.. Because, I find it pretty hard to believe you can't sell this house and buy the same sq ft. in a different house and come out tens of thousands of dollars add in the end. Hence, emotion driven.
Do you really think rising the roof makes financial sense? Honest question.
Given that you have a ceiling and roof on top of block walls, you might have a house mover look at the project. They may be able to come up with a clever way of doing it.
-- J.S.
" I just wanted more than someone stating the obvious. "
CAG already did.
He said Call an engineer.
did U do that yet?
I'm thinking no.
step one ... turn off the internet and call an engineer.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
"I cannot build under it because it has block walls. It seems that the previous owners built a basement and even added floorjoists to it, then popped the trusses on top of the floor, some walls, presto, a house. "To clarify. Are you talking about a you have what was done in some cases years ago? They build a basement and then put a roof on it and live in the basement for a few years. Then tear off the roof and build the first floor and new roof..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I don't know if this is true anymore but when I was a kid growing up in Ohio more than a few people built vacation homes that way. Seems the State/Counties etc. didn't tax basements as dwellings. So people summered in the basements of their "Future" 3 story house for a lot of years."Poor is not the person who has too little, but the person who craves more."...Seneca
Many places now have zone codes and require COO so it doesn't happen as much.But I am sure that it is still down "out in the country" in areas without codes.About lifting a truss roof. Several years I saw this on a TV show, then I found a newspaper article about it. But I have forgotten the details.Large victorian house in FL was being restored. Almost done and they had a serious fire.They thought they could not afford to rebuild it.But they came up with a scheme where they rebuilt the roof, on the ground complete with shigle, using trusses. It was a very complicated roof.Then lifted the whole assembly into place on the 3rd floor. IIRC they claimed $50,000 in savings..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
By lifting the roof with a crane you're introducing all kinds of stresses the trusses weren't designed for. It's not that it can't be done, but if you don't want to have a catastrophe on your hands you need somebody who can quickly analyze your structure and tell you how to SAFELY attach the crane.
A 24x36 roof may not be huge, but it's big enough to be heavy. You don't want to screw around with this. If you don't want to pay for an engineer, or can't find one, then just demo the roof and start over. With a stick-framed roof there are rules of thumb but with a truss roof there isn't.
Why not raise the whole house and build under it. Is the existing foundation up to par for a two story?
Mike
Trust in God, but row away from the rocks.
there you go thinking outside the box again - or should I say under the box :-)"it aint the work I mind,
It's the feeling of falling further behind."Bozini Latinihttp://www.ingrainedwoodworking.com
The other option might be to lower the ears. ; ^ ) Mike
Trust in God, but row away from the rocks.
There are 2 feature articles on the Jlc website in the research dept, under framing & structure. I tried to log into them but something seems to be up! I hope you find what your looking for!
The question could be, why do you wish to do it?
I am sure there are possibly good reasons, so likely very emotionally motivated.
I would bet you could sell the small house and buy one with twice the sq ft and a better layout than to rasie the roof. So is the reason to raise the roof emotional?
It sucks to raise a roof for an Add-A-level with a trussed roof because now your whole ceiling and sheetock has to come out. If it was stick framed you don't have to touch the whole ceiling and the sheetrock stays.
By the time you try and figure out or call an Architect or Engineer to brace off this roof with material and labor, and then lift it with a crane and pay for a crane, and then the crane has to come back after the walls are up and pay for the crane again, the whole roof can be stick framed and dried in in 1/2 a day or one day depending on what size crew you have and how much experience they have.
Or, you can have new trusses made and sitting on the job before you even rip the roof off.
Joe Carola
Edited 9/20/2007 6:17 pm ET by Framer
How much do you have to spend on the project?
sobriety is the root cause of dementia.
This site ranks way up there on the "I don't really have anything to add but I'm going to reply anyway" scale. You're getting it in spades. Kudos to CAGIV and Joe and maybe one other for actually trying to answer.
In my opinion you could probably prep and pick that roof with a crane, but like a few others have said it will be much simpler just to demo it and start over with new trusses, plywood, and roofing. At a minimum you will have to demo all of the sheetrock from underneath, and damage part of the roofing to get straps thru to your pick points. You will have to damage some of the interior wall finishes to get your pick points in. You'll have to hire a very large mobile crane, and they are EXPENSIVE if anyone will even take the job. You need them to come to the job twice, and you need to have a place to set the roof down.
I've seen a few articles about doing this, but it didn't look worthwhile to me. Raising the entire house might actually be a simpler job, even with the block walls.
Removing the roof as a unit, while technically possible, could easily cost more than the alternatives. You are saving the costs of demo, and the cost of new trusses, sheathing, and roofing. But you are adding a lot of other costs, and extra time, and most importantly extra risk.
First, you don't want do this without an engineer, or at minimum a good rigging company. The roof will have zero strength perpendicular to the trusses, and little shear strength in the horizontal plane once detached from the house. You will need the engineer to design and sign off on a lifting structure that doesn't load them incorrectly and will hold the load. That's $$$. The structure itself will likely require substantial materials and time to build and install.
Second, the labor element is going to hurt you. The odds are that this will be the first time anyone in the crew has done this. You will want a first rate crew ($$$), and they will have to do more 'stop and think' moments than they'd have to do in a normal job. There are a lot of time consuming details to slow things down, and a lot of opportunity for surprises. Budget time for them.
You should plan on the structure warping while it's off. Even if you somehow don't put extra stress on it, wood moves and residual stresses are everywhere.
Risk is the key element here. If everything goes right, you *might* save money. Your downside risk is that you pay a lot more than what you budgeted. Think double or more. Do you eat the extra cost? Will that kill the profit on this job? Put you out of business? Or just really piss off a customer?
I should admit that I'm not totally without experience in this. When I lived in rural Ohio a friend tried doing this with a shed (10x12). He was moving it, and the whole thing was too much weight for the trailer. So the roof had to go separately. Getting at the nails was a pain; there wasn't much access for the saw. We missed a few and didn't notice until we tried to lift. Nailing it back was worse; we ended up using 1/4" lag screws and a ratchet. He used a pair of 4x6s tucked in the outside corners of the trusses with 2x4 spacers to keep them separated. Used a high lift forklift with slings and fork extenders to take the roof off. Almost tipped the forklift. The dang thing warped (must have been residual stress in the lumber) and it went out of square enough that two corners were hanging more than 2" over the edge of the frame. Squaring it took a lot of work. I (um I mean he :-) ended up popping a bunch of the nails attaching the sheathing when trying to square it with ratcheting tie down straps. The end result was good enough to keep a a small tractor dry, but I sure wouldn't want to live in it.
Sure, this project was done in a pretty casual way by a bunch of rednecks, but it was a small shed and we were pretty high grade rednecks :-) In the end the shed was free, and we'd figured we'd just burn it down if it didn't work out.
A bigger roof will have more problems, and I hope you don't plan to burn the house down if it doesn't work. :-) I have no doubt that you'll want a better result that what we were willing to settle for.
Bosshog and I had a discussion about this a few eeks ago, I plan on adding a level to my house as well.
My plan was to demo the roof and replace with attic trusses. But in my case I wanted a bigger room than standard attic trusses would provide. So I thought of where the knee walls usually are in an attic truss and using that as my bearing point. Gives me a full width room, but also gives me a 5-6' overhang.
Then Boss mentioned raised heels. THat would squeeze the room dimensions down a little and cut the overhang down as well. I have framed a few houses with raised heels on attic trusses and the thought never crossed my mind.
Matt
I don't have all the answers, but I do have a few things to add.
First off, I think your roof probably weighs somewhere around 6,500 pounds, assuming a 4/12 pitch. The trusses are about #100 each, roofing #250/square, sheathing about #1,600. Adding #350 for fascia, blocking, and misc. lumber you have a structure that weighs ~6lbs. per square foot.
Cutting the roof loose and picking it up is certainly possible, but I bet it will take more time and money that what you will save.
You will absolutely lose the sheetrock attached to the bottom chords of the trusses. I can't imagine that you could keep any sheetrock intact and in decent shape, so I would just write that off.
Cutting the roof free may be somewhat of a pain with the sheathing still attached.
A decent size crane will be required with two or four spreader bars. I would think this is going to cost around a grand for everything involved. You need to make sure you can get a crane in and there are nor overhead obstructions to work around. You also will need a place to sit the roof down without moving the crane. Your temporary site will need to be pretty close to flat, preferably level. Even if it looks almost perfect I would probably plan to use shoring and a transit or laser to make a level pad.
You will need a pretty good amount of lumber to give the crane some points to pick the roof up in such a way that it won't rack the trusses and cause damage. An engineer or serious over-engineering will be required. Keep in mind the potential for bodily harm or damage to the existing structure. Neither are points to be taken lightly.
Once the trusses are removed, I would be concerned about the interior partitions staying straight. If you have a bedroom that is 12' wide your partition will probably stay somewhat straight, but if there's a wall that has not intersecting partitions for a decent span I would want to brace it somehow to keep everything in line since the trusses are not holding the top plate parallel to the exterior wall.
When you get the floor framed and the second floor exterior walls up, you have to call the crane out again to pick up the assembly. Hopefully nothing funny has happened and it will sit back down flat and you don't have out of square problems. I'm guessing that you will still have to replace a square or two of shingles and several sheets of plywood from the holes cut in the roof for the move.
It may work out just fine, but it could be a mess.
The attached pics show a garage with a bonus room above that we did in a somewhat similar manner. We put the sill plates on the garage stem walls and framed the exterior walls and set them down on the garage slab. Then we set the trusses on top of that and sheathed the roof, finished the dormers, and installed the felt. I think we saved some time but there were certainly some risks involved. The trusses were new so I was not as concerned about how they handle the move since they didn't have 40 years of stress and moisture differentials in them.
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
Jon, that's hot! I'm sure it was stressful and lots of fun too. Did you have a PE design the rigging?
Better up your insurance. With those pics it looks so easy a caveman could do it.
No PE was within several miles of that site. The pic is from about five years ago and things were much different then. We were actually working for a GC who gave the OK for the whole thing and kinda assumed liability. The PM for that job (the GC's SIL) was an over-the-top take charge guy (his favorite phrase was "this ain't my first rodeo" said with a Wyoming drawl) so we just let him micro-manage the rigging & lifting stage.If we had to do it again, I don't think it would be much of a big deal. I'm sure our truss guy would be able to work with us as far as lifting points and such. We used some 6x6's but I would probably invest in some LVL's were we to do it again.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Another complication.It is not clear to me if this roof is over just a basement or the first floor. But if it is over the first floor then that means that interior walls are not load bearing and the beam below only carries the first floor load. That beam needs to be reinforced and the interior walls might need to be restructured.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Assuming that all of the other potential problems have been worked out and it is practical to do this I wonder if a "blitz" build would work.That is get have the exterior walls already framed and sheathed. And either have floor section prebuilt or all of the material staged and lot so people.The lift off the roof, either smwarn it with people or use the crane to drop in the floor section and then the walls. Then the crane to set the roof back.What my thoughts are that if you are getting the crane out and having to pay minimum charges anyway, why not keep it their and do all at one time rather than have 2 minimum/setup charges.And reduces the time that it is exposed to the weather..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I'm sure it could be done. Obviously you're going to want very thorough planning.Protection from the elements is very nice but I would want to feel really good about the condition of the trusses and shingles.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
"How do I do this without damaging the existing roof?"
You don't. You're going to have to put at least 4 holes in the roof. You may be able to use eye bolts for the lift points, but...
You may also have to remove the bottom rows of sheathing so you'll have room to connect the roof to the new walls. You may be able to cut between the wall top plates and let the upper one fly with the roof, then frame the new walls with one top plate.
First step is contact the original truss manufacturer or an engineer. They will design the internal bracing, which may consist of 1 or 3 lateral pieces and a bunch of diagonal braces. Their placement is critical and specific to your roof.
They will also size and tell you where to place the bearing beams the crane will hook to.
While the engineering is happening, you might as well strip *all* the second floor drywall and trim. This will let you make some accurate measurements.
If you have the ground space, set up two level areas, one for the roof and one for constructing the second floor. If you can, frame the entire second floor on the ground. You will need to let the floor truss manufacturer know that you will be lifting the complete structure in place, so they can figure out some lift points. You'll have to put the lift beams down under the floor and size them so they all fit between any first floor walls.
If you can't frame the entire second floor, at least frame and sheath all the walls and have a big crew to set and sheath the floor. You can plan on a double rim joist and pre-assemble the floor in 12' sections. Leave off the sheathing the would cross the sections. The second rim joist would tie all the sections together.
When the crane gets on site, pick the roof off, lift the second floor in place and stab some all thread through the second floor bottom plates and first floor top plates, then lift the roof back in place and connect it.
SamT